This is a Phase I study to develop a molecular assay for the genetic differentiation of the major HIV-1 subtypes in plasma and PBMCs. The assay involves a RT-PCR based capture hybridization format compatible with the microplate ELISA technique. Biotin-labeled gag and env PCR products will be captured on microtiter wells containing bound oligonucletide probes and detected by colorimetric reaction. Probes representing different sequences of the gag and env genes will be used to distinguish different strains of HIV-1 from both M and O groups.